Five deaths so far.
It seems our new serial killer friend lacks Sleight's grace. Sleight could get to his targets through a Door, making his progress untraceable. This new copycat killer apparently doesn't have that luxury. He breaks into their homes and slits their throats there.
Oh, and two of the victims weren't Servants. One was being followed. The other had no connection to Master whatsoever.
Sloppy. Very sloppy. We should catch this guy soon.